Abstract
Pistachio is one of the garden products that its product is affected by temperature fluctuations. Failure to chilling requirements of flower buds, spring frost, lack of effective pollination and fertilization, as well as the sickling of the fruit and its bursting are the consequences of temperature fluctuations in pistachio. The present study was carried out in order to evaluate four commercial cultivars of pistachio to circadian temperature fluctuations in laboratory conditions in two consecutive years. The factors included the cultivar in four levels ('Akbari', 'Ahmad Aghaei', 'Kale Ghochi' and 'Sefid Pistaha Nug'), and the number of temperature fluctuations in 4 levels (without temperature fluctuations as a control, 2, 4 and 6 temperature cycles). The results showed that in the cultivar 'Kale Ghochi', 4 and 6 temperature cycles caused an increase in ion leakage in shoots and buds compared to the control, while in other cultivars no significant difference was observed between the temperature cycle and the control, which indicates the greater sensitivity of the 'Kale Ghochi' cultivar compared to other cultivars to temperature fluctuations. Comparing ionic leakage rate of shoots and buds in temperature cycles showed that the buds had less ionic leakage than the shoots.